Helmet core



FIG. 1 is a front, top perspective view of a helmet core, showing thenew design;

FIG. 2 is a front view thereof;

FIG. 3 is a rear view thereof;

FIG. 4 is a left view thereof;

FIG. 5 is a top view thereof;

FIG. 6 is a bottom view thereof; and,

FIG. 7 is a bottom, rear perspective view thereof.

The broken lines depict parts of the helmet core that form no part ofthe claimed design.

CLAIM The ornamental design for a helmet core, as shown and described. 